DC-DC converter and driving method thereof

1. A DC-DC converter comprising: a first inductor configured to output a first inductor current based on an input voltage; a second inductor configured to output a second inductor current based on the input voltage; an output network unit configured to provide a first output voltage to a first output terminal and provide a second output voltage to a second output terminal, based on the first inductor current and/or the second inductor current; a controller configured to determine cross-regulation with respect to the first output terminal and the second output terminal and generate a mode signal based on the determination; and an inductor network unit configured to: electrically connect the first inductor and the second inductor in series between an input terminal and the output network based on the mode signal corresponding to a first mode, and electrically connect the first inductor between the input terminal and the output network unit and electrically connect the second inductor between the input terminal and the output network unit in parallel with the first inductor based on the mode signal corresponding to a second mode.

2. The DC-DC converter of claim 1 , wherein the inductor network unit comprises a serial mode switch that includes one terminal connected to the first inductor and the other terminal connected to the second inductor and is switched off by the controller when the first inductor current or the second inductor current is greater than a threshold current after a reference time from a charging time point of the first inductor and the second inductor.

3. The DC-DC converter of claim 2 , wherein the inductor network unit further comprises: a first isolation mode switch including one terminal connected to the first inductor and the other terminal connected to the output network unit; and a second isolation mode switch including one terminal receiving the input voltage and the other terminal connected to the second inductor, wherein the first isolation mode switch and the second isolation mode switch are switched on by the controller when the first inductor current or the second inductor current is greater than the threshold current after the reference time from the charging time point.

4. The DC-DC converter of claim 3 , wherein the output network unit comprises: a first normal output switch including one terminal connected to the second inductor and the other terminal connected to the first output terminal; a first split output switch including one terminal connected to the first isolation mode switch and the other terminal connected to the first output terminal; a second normal output switch including one terminal connected to the second inductor and the other terminal connected to the second output terminal; and a second split output switch including one terminal connected to the first isolation mode switch and the other terminal coupled to the second output terminal.

5. The DC-DC converter of claim 1 , wherein the controller comprises: a mode control unit configured to sense the first inductor current and the second inductor current to generate the mode signal and a clock modulation signal; and a switch control unit configured to control the output network unit and the inductor network unit based on the mode signal and the clock modulation signal.

6. The DC-DC converter of claim 5 , wherein the mode control unit comprises: a cross-regulation detector configured to output a cross-regulation signal when the first inductor current or the second inductor current is greater than a threshold current after a reference time from a charging time point; a clock modulator configured to increase a pulse width of the clock modulation signal based on the cross-regulation signal; and a mode converter configured to generate a mode signal based on the cross-regulation signal.

7. The DC-DC converter of claim 6 , wherein the mode signal comprises an isolation mode signal, wherein the mode converter generates the isolation mode signal when receiving the cross-regulation signal, wherein the switch control unit electrically isolates the first inductor and the second inductor based on the isolation mode signal.

8. The DC-DC converter of claim 6 , wherein the mode control unit comprises: a first current counter configured to generate a first discharging time signal by measuring a first full discharging time at which the first inductor current is below the threshold current; and a second current counter configured to generate a second discharging time signal by measuring a second full discharging time at which the second inductor current is below the threshold current.

9. The DC-DC converter of claim 8 , wherein the mode signal comprises a serial mode signal, wherein the mode converter receives the first discharging time signal and the second discharging time signal, and generates a serial mode signal when the first full discharging time is greater than a first stabilization time and the second full discharging time is greater than a second stabilization time, wherein the switch control unit electrically connects the first inductor and the second inductor based on the serial mode signal.

10. The DC-DC converter of claim 5 , wherein the controller further comprises an output control unit configured to compare the first output voltage with a first reference voltage to provide a first output control signal to the switch control unit and compare the second output voltage with a second reference voltage to provide a second output control signal to the switch control unit.

11. A DC-DC converter driving method comprising: connecting, by an inductor network unit, a first inductor and a second inductor in series between an input terminal and an output network unit based on a serial mode signal; providing, by the output network unit, a first output voltage to a first output terminal and a second output voltage to a second output terminal, based on an inductor current flowing through the first inductor and the second inductor; generating, by a controller, an isolation mode signal when the inductor current is greater than a threshold current after a reference time from the charging time point of the first inductor and the second inductor; electrically disconnecting, by the inductor network unit, the first inductor and the second inductor based on the isolation mode signal; and providing, by the output network unit, a third output voltage to the first output terminal based on a first inductor current flowing in the first inductor and a fourth output voltage to the second output terminal based on a second inductor current flowing in the second inductor.

12. The method of claim 11 , wherein the providing of the first and second output voltages comprises: providing the first output voltage for a first reference time; and providing the second output voltage for a second reference time after the first output time.

13. The method of claim 11 , wherein the generating of the isolation mode signal comprises extending the reference time until the inductor current has the same value as the threshold current.

14. The method of claim 11 , wherein the generating of the isolation mode signal comprises: sensing the inductor current by the controller; generating a high-level cross-regulation signal when the inductor current is greater than the threshold current; and converting the serial mode signal into the isolation mode signal based on the cross-regulation signal.

15. The method of claim 11 , wherein the providing of the third and fourth output voltages comprises simultaneously charging the first inductor and the second inductor based on the isolation mode signal.

16. The method of claim 11 , wherein a voltage level of the first output voltage and a voltage level of the third output voltage are the same, and a voltage level of the second output voltage and a voltage level of the fourth output voltage are the same.

17. The method of claim 11 , further comprising: measuring, by the controller, a first full discharging time at which the first inductor current is below the threshold current and a second full discharging time at which the second inductor current is below the threshold current; generating, by the controller, the serial mode signal when the first full discharging time is greater than a first stabilization time and the second full discharging time is greater than a second stabilization time; and connecting, by the inductor network unit, the isolated first and second inductors in series based on the serial mode signal.

18. The method of claim 17 , wherein a magnitude of the threshold current is zero and the first stabilization time and the second stabilization time are dependent on the reference time and an inductance of the first and second inductors.